PROBLEM CREATING INCREMENTALS

I HAVE CREATED A SUCCESSFUL FULLBACKUP ON AN EXTERNAL DRIVE.
I AM CONFUSED WHEN CREATING A ONE TIME A WEEK INCREMENTAL BACKUP.
AFTER ENTERING ALL REQUIRED DETAILS OF DATE & TIME FOR INCREMENT BACKUP, AN INFO INPUT SCREEN ASKS FOR USER NAME..WHICH I GIVE, THEN IT WANTS A PASSWORD WHICH I ENTER...
IMMEDIATLY & CONSISTANTLY GET THE SAME SCREEN...(."WARNING" LOGIN INFO IS NOT CORRECT).
I AM ENTERING MY OWN NAME (RTMILLS) AND USE A PASSWORD.., I AM CONFUSED/DENSE/STUMPED......ANY HELP PLEASE RTM...TNXS

depends on whether or not you used a password when you created the original archive which you are now trying to append to incrementally. Try leaving them blank and see if it will proceed without error. If you are talking about the very last password prompt make sure your computer name preceeds your username and see if that will work...(ie) DESKTOP\username
where DESKTOP = your computer name
include backslash and username = your login name
hope this helps